1. Field of the Invention
The present invention relates to a honeycomb structural body and an exhaust gas treating apparatus.
2. Discussion of the Background
Conventionally, various kinds of exhaust gas treating apparatuses for internal combustion engines of vehicles, construction machines, or the like have been proposed and put to practical use. A typical exhaust gas treating apparatus includes an exhaust pipe communicating with an exhaust gas manifold of the engine. In the middle of the exhaust pipe, there is provided a casing made of, e.g., metal, and a honeycomb structural body is provided inside the casing. The honeycomb structural body captures particulates in the exhaust gas, and functions as a filter (DPF: diesel particulate filter) for purifying the exhaust gas or as a catalyst carrier for converting toxic gas components in the exhaust gas with a catalyst reaction.
For example, if the honeycomb structural body were used as a DPF, the honeycomb structural body would include plural pillar-shaped cells extending in a lengthwise direction, which cells are partitioned by porous cell walls. Each cell is sealed by a sealing material at one end. Thus, the exhaust gas introduced inside the honeycomb structural body inevitably passes through the cell walls before being exhausted from the honeycomb structural body. Accordingly, it is possible to capture the particulates in the exhaust gas as the exhaust gas passes through the cell walls. If the honeycomb structural body were used as a catalyst carrier, the lengthwise surface of each cell wall is provided with a catalyst carrying layer and a catalyst. Toxic gas such as CO, HC, and NOx included in the exhaust gas is converted by this catalyst. Typically, a holding seal member made of an inorganic fiber mat is provided between the honeycomb structural body and the casing. This holding seal member prevents the honeycomb structural body from breaking as a result of contacting the casing (JP2005-125182A). The entire contents of JP2005-125182A are hereby incorporated by reference.